The present invention relates to a ventilation system for a lamp assembly, such as an automotive headlamp, fog lamp, signal light, or taillight. More specifically, it relates to a lamp assembly having an optical and/or non-optical shield coupled to a ventilation air passage, such that a cavity of the lamp assembly may be ventilated to an ambient environment.
A concern that frequently arises during the design of automotive lighting devices is the need to provide proper ventilation for an interior of a housing or body of the lighting device. While adequate ventilation is important for both lighting device functionality and appearance, the automotive lighting device design should also take into account the prevention of fogging of the lighting device lens. Device design should also take into account the unwanted penetration of water, dirt, dust and other contaminants from a surrounding ambient into the lighting device cavity. These design concerns can be especially important where the lighting device resides on the exterior of an automobile that is subject to high speeds, inclement weather, and high water pressure situations (e.g., a car wash).
Such design concerns also arise when designing an optical and/or non-optical lighting device to ventilate internally generated heat. For example, during use, a bulb of a typical lamp reaches relatively high temperatures. Heat transferred from the bulb can melt, deform, or otherwise damage the lamp housing surrounding the bulb, especially when the lamp housing is made from an inexpensive plastic material. While any side of the lamp housing may have one or more areas susceptible to heat damage, the top side of the lamp housing above the bulb generally suffers the greatest damage due to heat transfer by free, or natural, convection from the bulb.
A known method of ventilating lighting devices is to provide the lighting device with a system of chicanes, labyrinths or air ducts that create a tortuous path. Such a known device is disclosed in U.S. Pat. No. 5,758,957 to Perrotin which is herein incorporated by reference and to which the reader is directed for further details. In this known device, a labyrinth path is provided. This path is an air passage provided with a number of angles. This labyrinth passage deters ingress of moisture and dust but, at the same time, allows air transfer between the lamp and the environment to equalize pressure and, if applicable, transfer heat. In other words, this allows the lamp to xe2x80x9cbreathexe2x80x9d while also reducing the potential for fogging and condensation.
Such known lighting devices have a number of manufacturing and design disadvantages. For example, where the lighting device is an injection molded device, creating a torturous path in an injection molded part may be difficult. Creating a passage of two complete or more 90xc2x0 turns with a single tool injection molded component creates manufacturing complexities because it requires more than one die draw direction.
Other known ventilation designs utilize additional rubber parts to provide a torturous path, such as a macaroni tube, that attaches snuggly to a vent boss on the housing. The addition of a number of rubber parts also add cost in the form of material, assembly time, and warranty/quality because these vents often fall off or are forgotten. Extra lamp device pieces also increase the overall weight of the device.
Accordingly, it would be desirable to have a lighting device ventilation system that overcomes the problems associated with known systems.
There is a general need for reducing the cost of a lighting device system. There is also a need for a vent system that does not require a macaroni or other angled tube. There is a further need for combining lamp components while also reducing the complexity of molding tools.
The present invention provides a lamp assembly including a lamp housing defining a cavity. The lamp housing has at least one side with a vent passage. A heat shield is coupled to at least one side and at least partially aligned with the vent passage to provide ventilation to the lamp housing.
In another embodiment, a vehicle lighting device includes a lamp housing defining a cavity. The lamp housing has at least one side provided with a ventilation opening. A bulb shield insert that has an attachment mechanism is at least partially aligned with the ventilation opening. The attachment mechanism at least partially allows for ventilation of the cavity. A bulb shield stem extends from the bulb shield insert. The bulb shield stem has a bulb shield cover adapted to at least partially cover a bulb.
A method for ventilating a lamp assembly is also disclosed. The method includes defining an internal cavity of a lamp housing. A vent passage is provided in a side of the lamp housing. A heat shield is coupled to the at least one side; and at least partially aligning the heat shield with the vent passage to provide ventilation to the lamp housing.